在 2019年10月27日 +0800 PM1:43，Eli Zaretskii <eliz@gnu.org>，写道：

But the question is: do both events you mention arrive with any time
interval between them, or do they arrive together? IOW, the issue is
about timing, not about the number of events.

I guess that the two events arrive with very small time interval or together. They are processed by emacs one by one,  and cause emacs to redisplay twice when redisplay-dont-pause is t.